Adolescent drug abusers are particularly at high risk for HIV/AIDS infection. Therefore substance abuse treatment provides a prime opportunity for intervention on HIV/AIDS risk behaviors within this population. Unfortunately, very few youth with drug abuse or dependence in the United States receive treatment. This population of untreated youth represents a massive "treatment gap" in adolescent health care that renders impotent a potentially important avenue for preventing HIV/AIDS. While the juvenile justice system represents a prominent path linking drug-abusing adolescents with treatment services, its shortcoming lies in the fact that only one fifth of the adolescents who need treatment each year are apprehended by the legal system. As a result, large numbers of youth in need of treatment go undetected by the most typical entry way into the system. Moreover, the lack of motivation for treatment characterizing most adolescent drug abusers significantly decreases the likelihood these youth will enter treatment, barring mandates from the legal system or other social institutions. These adolescents represent a sizeable and, heretofore, overlooked population of treatment-elusive youth. Given that effective prevention of HIV/AIDS infection and concomitant adolescent substance abuse treatment require that we first successfully engage these youth in treatment, the current proposal puts forth two distinct, but related, studies. Study 1 evaluates, through random assignment of 140 parents, the efficacy of a promising engagement approach, Community Reinforcement Training, versus Engagement As Usual. Study 2 will evaluate the efficacy by which an HIV/AIDS preventive intervention, embedded in a family-based drug abuse treatment, successfully affects both health-related outcomes for youths successfully engaged through Study 1. This study further addresses an important priority by examining how the components of the HIV and family interventions interact clinically, and how they might be combined in ways that enhance their potency relative to adolescent HIV/AIDS-risk behaviors. Understanding how the core mechanisms of the family and HIV interventions work together will provide heuristic value by informing ongoing efforts to refine and integrate interventions for the drug use and HIV/AIDS risk behaviors of adolescents.